Abstract: This invention discloses a seal arrangement between an outdrive unit and a hull of a vessel, comprising an outdrive unit connected to an engine and mounted on a bed of the hull, the outdrive unit projecting downward through an opening in the hull; a diaphragm seal fixed to the hull and the outdrive unit for sealing a space between the hull and the outdrive unit; an annular seal flange projecting above the diaphragm seal from the bed toward the outdrive unit; and a ring seal arranged between the outdrive unit and the seal flange for sealing a space therebetween; characterized in that; both ends of the ring seal are fastened to the outdrive unit and the seal flange, respectively. A water sensor connected to a warning device is arranged in a space between the diaphragm seal and the ring seal.

Abstract: A reduction and reversing gear for marine propulsion systems making use of the clutch case of a conventional reduction and reversing gear of a type having an input shaft mounted on an upper part of the clutch case, an output shaft extending in parallel with the input shaft and mounted on a lower part of the clutch case, a multiple disc clutch carried by the input shaft, a small gear rotatably carried by the input shaft and adapted to be connected to and disconnected from the latter by the multiple disc clutch, and a large gear carried by the output shaft and engaging the small gear. A planetary gear type reduction gear is disposed in the space around the output shaft and below the multiple disc clutch to make an efficient use of that space, thereby to provide an additional reduction stage between the large gear and the output shaft.